Injury mortality among Iowa farmers, 1980-1988: comparison of PMR and SMR approaches.

State and provincial proportional mortality studies in the United States and Canada have found increased ratios of overall injury mortality among farmers, including occupational injuries and other unintentional injuries, such as those from motor vehicle crashes and fires, as well as suicides. In contrast, Scandinavian standardized mortality (morbidity) studies have found no increase in the injury fatality or morbidity ratios of farmers in comparison with the rest of the population. This study reviews the injury mortality of Iowa farmers for the years 1980-1988. Among white male farmers, we found an increased proportional mortality ratio for all injuries of 1.26 (95% confidence interval (CI) 1.21-1.31). In part, this was a result of the increased proportional mortality ratio for at-work injuries of 3.77 (95% CI 3.35-4.24), but there were also elevated proportional mortality ratios for such nonoccupational injuries as suicides, 1.20 (95% CI 1.09-1.32), motor vehicle crashes, 1.23 (95% CI 1.12-1.34), and electrocutions, 1.78 (95% CI 1.08-2.95). For younger farmers aged 20-64 years, we calculated standardized mortality ratios as well. The standardized mortality ratios were generally within 10% of the proportional mortality ratios, which suggests that the differences between North America and Scandinavia are not the result of methodological differences, but are more likely related to differences in environmental exposures and safety practices.